1.1 Field of the Invention
The present invention relates to systems and methods for both voice messaging and speech recognition. More particularly, the present invention is a voice messaging system and method responsive to speech commands issued by a voice messaging subscriber.
1.2 Description of the Background Art
Voice messaging systems have become well-known in recent years. A typical Voice Messaging System (VMS) interacts with a subscriber through a Dual-Tone Multi-Frequency (DTMF), or touchtone, voice messaging User Interface (UI). During subscriber interactions, the VMS issues a voice prompt requesting the subscriber to press one or more DTMF keys to initiate corresponding operations. In the event that the subscriber presses a valid DTMF key sequence, the VMS performs a particular set of operations.
Under certain circumstances, it may be inconvenient or even dangerous for a subscriber to focus their attention on a keypad. For example, in a wireless telephone environment where a subscriber is driving or walking while on the telephone, requiring the subscriber to select an option from a set of DTMF keys could result in an accident or difficult situation. As a result, systems and methods have been developed for using speech as a means for providing hands-free interaction with a VMS, through speech-based selection of commands, user interface navigation, and entry of digits and/or digit strings.
Those skilled in the art will recognize that a conventional DTMF voice messaging UI usually has a fairly complex or extensive hierarchy of menus. Some systems that provide speech-based VMS interaction simply implement a speech UI having an identical or essentially identical menu hierarchy as a conventional DTMF UI. When a subscriber must concurrently perform multiple tasks, such as driving and VMS interaction, reducing the complexity of lower-priority tasks is very important. Thus, systems that implement a speech UI in this manner are undesirable because they fail to reduce VMS interaction complexity.
Those skilled in the art will recognize that speech recognition is an inexact technology. In contrast to DTMF signals, speech is uncontrolled and highly variable. The difficulty of recognizing speech in telephone environments is increased because telephone environments are characterized by narrow bandwidth, multiple stages of signal processing or transformation, and considerable noise levels. Wireless telephone environments in particular tend to be noisy due to high levels of background sound arising from, for example, a car engine, nearby traffic, or voices within a crowd.
To facilitate the successful determination of a subscriber's intentions, speech-based voice messaging systems must provide a high level of error prevention and tolerance, and significantly reduce the likelihood of initiating an unintended operation. Speech-based voice messaging systems should also provide a way for subscribers to successfully complete a set of desired voice messaging tasks in the event that repeated speech recognition failures are likely. Prior art speech-based voice messaging systems are inadequate in each of these respects.
The difficulties associated with successfully recognizing subscribers' speech and determining their intentions necessitates a high level of support and maintenance to achieve optimal system performance. The availability of particular speech recognition data and system performance measures can be very useful in this regard, especially for system testing and problem analysis. Prior art systems and methods fail to provide an adequate means for flexibly controlling when and how speech recognition data and system performance measures are stored and/or generated. Moreover, prior art systems and methods fail to collect maximally useful speech recognition data, namely, the speech data generated during actual in-field system use. What is needed is a speech-responsive voice messaging system and method that overcomes the shortcomings in the prior art.